In a device forming a so-called evaporation, there is a device forming a cylindrical liquid-receiving portion on an evaporation opening for allowing a lower space, into which a fuel enters, and an upper space, which is communicated with the ventilation flow path, to be communicated so as to prevent a fuel in a liquid state from leaking to the ventilation flow path. (See Patent Document 1) However, in such a device, because of a structure itself, although a fuel in a splash form injected into the upper space in the liquid-receiving portion can be received, it is difficult to prevent a fuel in a mist form which is lighter than the fuel in a splash form from leaking to the ventilation flow path.